ietf-xml-mime
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Re: Positions on "List of issues"

1999-04-13 23:28:58
At 20:02 99/04/13 +0800, Rick Jelliffe wrote:
My 2 cents worth:

Issue 1: Proposals for additional parameters in the past

I agree with Tim Bray that it is inappropriate to give the DTD in a
parameter: in particular, because XML content models are basically glorified
assert() statements. DOCTYPE declarations are fine and appropriate where
they are.

In particular, I think we are missing a key distinction that the MIME
content-type is not so much the "type" of a resource, but the type of a
particular *publication* of a resource.

Well, if it's to distinguish the PS version of a document from the pdf
version and from the HTML version, then you are certainly right. And
it should also be possible to serve something as text/plain if one
really wants. But in the general case, the idea is really that you
say what it is, and leave the rest of the choice to the user and it's
environment. Cases where this doesn't work are implementation problems,
not proofs of concept.


Furthermore, let me bring up another problem with parameters: the parameters
have to be sourced from somewhere: everytime we have to duplicate
information from inside an XML document into a header, we create the chance
for a mismatch.

Yes indeed. [I might come back to this point in another discussion :-]
The main distinction is: What do you want to be able to do without having
to look inside the resource. On many systems, having to look inside or not
is a big distinction in practical terms.

RFC 2376 should be revised when charsets for UTF-16 are registered.

Yes. And XML appendix F should be revised simultaneously, so that the
specifications are kept in sync.

Good point.


Issue 4: Characters .vs. bytes

An XML MIME entity is a sequence of characters as opposed to a
sequence of bytes.  RFC 2376 is not really clear about this.

This is the old question. When we discussed it before, didn't we say that:
* a text/xml entity is a sequence of characters
* an application/xml entity is a sequence of bytes?

I hope an application/* is not a sequence of characters.

Definitely not. In both cases, there are two levels, the character
level and the byte level. In both cases, XML is defined in terms of
characters, and not bytes. Therefore, in both cases, an XML document
is a sequence of characters. In both cases, when sent as a MIME entity,
it has to be sent as a sequence of bytes.

You are right that in the case of application/xml, the chance that
the bytes don't change is higher than in the case of text/xml, but
it is pretty high in both cases anyway.



Issue 6: Ambiguity of CCS conversion

If this is the case, it might make sense to introduce a parameter
"map" to precisely specify which mapping should be used.

This also could have bearing on the PUA (private use area) character
problem, and the problem of corporate character sets (e.g. Hong Kong's
GCCS).

Adding parameters will just increase the mess with current charsets.
It will send the message "it's okay to change a charset slightly, just
add a parameter". This is definitely not what we need!


Regards,   Martin.


#-#-#  Martin J. Du"rst, World Wide Web Consortium
#-#-#  mailto:duerst(_at_)w3(_dot_)org   http://www.w3.org

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